Exclusive video takes us deep into Crossrail's tunnels as the project speeds ahead

In 2013, we journeyed into the depths of Stepney Green, an interchange station where the Elizabeth line splits – west towards Central London, north east towards Pudding Mill Lane and south east past Canary Wharf to Woolwich. Earlier this year we returned to see how the huge cavern, drilled 35 metres below ground, has been transformed into a test line with trains running along it daily as part of the Crossrail project.